#537 Write relational algebra expression and SQL statements

Write relational algebra expression and SQL statements - Computer Science

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Free Chegg Question

Consider the following scenario. You are developing a fault management system. The database maintains the following information: Fault (fault_id,fault_type, fault_date) FaultType(fault_type, fault_description) FaultManagement(fault_id,technician_id, assigned_date) Technician(technician_id, name, age) Write relational algebra expression and SQL statements for the following:

i. Find all the faults with fault description

ii. Find the description of all the faults that occurred during Jan 2020-Dec 2020

iii. Find the name of the faults assigned to Aslam

iv. Group all the faults based on type, find their count and the average age of the technician managing it

v. Find all the faults that are not assigned to any technician

vi. Find the technician who has not been assigned any fault

vii. Find all the faults that end with ‘dead’

viii. Find the oldest technician

ix. Find the youngest technician

x. Find the second oldest technician

xi. Find the type of fault which has not occurred so far

xii. Find the number of faults assigned to each technician

xiii. Find the number of faults that occurred in every month of the year 2020

xiv. Find all the technicians who have not been assigned more than two faults

xv. Find all the faults, their type, assigned date, the technician details. Sort the faults based on the assigned date

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Only required an answer to question no.2

Question-2 marks [06] Read the above scenario, which describes the data requirements of the fault management system.

(a) Identify the main entity types in the given scenario.

(b) Identify the main relationship types between the entity types described in (a) and represent each relationship as an ER diagram.

(c) Determine the multiplicity constraints for each relationship described in (b).

(d) Determine candidate and primary key attributes for each (strong) entity type.

(e) Using your answers (a) to (d) attempt to represent the data requirements of the fault management system as a single ER diagram.

(f) Implement the above schema in one of the RDBMSs (in form of tables) you currently using.

Note: I just required an answer of question no.2 only. The reason of copying question no.1 is because the scenario is in question no.1.

Question-3 marks [04] Consider whether it is appropriate to introduce introduce the enhanced concepts of specialization/generalization, aggregation, and/or composition into the ER model for the case study described in question 1. If appropriate, redraw the ER diagram as an EER diagram with the additional enhanced concepts

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Free Chegg Answer

The EER diagram is posted below with the concept of specialization.